The present invention is directed to an apparatus for selectively applying tension to a parking brake cable in an automotive vehicle or the like.
Apparatus for selectively applying tension to a parking brake cable typically includes a lever, such as a foot lever, responsive to a vehicle operator for applying tension to a cable and thereby setting the parking brake. A hand-operated mechanism is provided for selectively releasing the brake. It is a general object of the present invention to provide an apparatus of this type in which the force applied to the parking brake cable is a variable function of operation of the lever. Another object of the present invention is to provide an apparatus of the described character that is readily adaptable for use in conjunction with a variety of vehicles, and in which the force characteristic of the apparatus may be varied for vehicles of differing sizes while maintaining commonality of parts. Yet another object of the present invention is to provide an apparatus of the described character having improved stability at the operating lever.
Apparatus for selectively applying tension to a parking brake cable in accordance with a presently preferred embodiment of the invention comprises a pulley for coupling to the brake cable and having a cable groove that is non-circular about the axis of rotation of the pulley. A lever is coupled to the pulley for rotating the pulley in one direction about its axis and thereby winding the cable into the groove to apply tension to the cable. A clutch is coupled to the pulley to prevent reverse rotation of the pulley, and a release mechanism is coupled to the clutch for releasing the clutch and thereby releasing tension in the cable. In the preferred embodiment of the invention, the non-circular groove has a maximum radius where the cable is wound into the groove upon initial operation of the lever, and a decreasing radius thereafter. In this way, force is applied to the parking brake cable at maximum rate upon initial actuation of the lever, increasing at a lesser rate as the lever is further depressed.
In the preferred embodiment of the invention, the pulley comprises first and second flat circular plates, with the cable groove being formed by a groove base carried by the second plate and groove sidewalls formed by the first and second plates. The first plate includes facility for attachment of the cable, and a spring is coupled to the first plate for maintaining tension in the cable after the cable has been released so that the cable will not be slack. The spring may comprise a coil spring that extends between peripheral portions of the first and second plates. Alternatively or additionally, the spring may couple the pulley to a shaft on which the pulley is mounted for rotation. The clutch in the preferred embodiment of the invention comprises a first helical spring that encircles a hub that extends from the first pulley plate. A second helical spring encircles a hub that extends from the opposing side of the first plate and operatively couples the lever to the pulley. The lever preferably has a pair of legs rotatably mounted on the hub on opposite sides of the second helical spring for adding stability to the lever, which may be either of one-piece construction or a two-piece assembly. The pulley mechanism is mounted for rotation on a mounting plate, and a bracket enclosing the pulley mechanism. The second helical spring has opposed ends coupled to the bracket and the lever for transferring operation of the lever to rotation of the pulley.